Armored reenforced-concrete slab



April 17, 192

J. A. VOSKAMP ARMORED REENFORCED CONCRETE SLAB Filed Oct. 25. 1926.

ATTORNEY Patented Apr. 17, 1928.

I UNITED STATES PATENT OFFICE.

JOHN A. vosxnmr, or new YORK, N. Y., ASSIGNOR 'ro IRVING IRON WORKS comm, A CORPORATION on NEW YoRK.

ABMORED BEENFORCED-CONCRETE SLAB.

This'invention is an im rovement on the structure described in U. Patent to Walter E. Irving, No. 1,524,035 dated January 27, 1925, and is designed to reduce the weight of such structure without correspondingly decreasing its strength. It is particularly designed for use on bridges inwhich the floor plates or slabs rest on sills extending crosswise of the bridg; The best form of apparatus at present own to me embodying my invention and certain modifications thereof, are illustrated in the accompanying sheet of drawings in which Fig. 1 is a diagrammatic plan viewof a part of a bridge structure with cross sills, showing a art of the reenforced flooring, parts being roken away.

Fig. 2 is a perspective skeleton view on a larger scale showing certain extended skeleton bars serving as vertical spacing elements.

Fig. 3 shows a modification of the structure shown in Fig. 2 in which lower horizontal spacing strips have been omitted and all straight bars extended in skeleton form.

Fig. 4 shows a further skeletonized modification.

Throughout the drawings like reference characters indicate like parts. 41, 41, represent the trusses of a bridge the deck or floor 43 of which is supported by cross sills 42, 42. Said deck or floor is formed by reenforced concrete slabs or sheets stretching across from one sill to another. The invention relates to the reenforcement of these concrete slabs, and comprises a grating embedded in the concrete at or near the upper surface thereof and serving as a skeleton armoring for said surface and as means for distributing the shearing stresses created by a concentrated load, and a set of tension reenforc ing members parallel to the longitudinals of said grating, supported therefrom, and embedded in the lower portion of the slab. These lowertension reenforcing members may be connected together to form a second grating. In any case they are supported from the upper grating by skeleton means to save weight.

The grating embedded in the upper surface of the slab is preferably formed of parallel straight bars 31, 31, spaced apart by 1ntervening bent strips 33, these elements be ing riveted together as shown at 35, 35. One form of tension reenforcement for the lower portion of the slab consists of the straight bars 32 and 32", shown in Fig. 2, these beingconnected-together by intervening bent strips 34, "34, to form a second grating which issupported from the upper grating by extendng certain of the bars marked 32 vertically in skeletonized form so that their upper portions may serve as certain of the straight bars for the upper grating. Preferably the I skeleton structure is formed by stamping'or cutt ng out portions 40, 40,- from the medial section of each wide bar. 37 is a body of concrete fillingthe meshes of both gratings and the space between gratings, including the cut-out spaces 40, 40.

Where great rigidity is required all of the straight bars 31' may be extended in skeleton form to serve as tension members 32,

as shown in Fig. 3. In such case, the lower bent spacing strips may be omitted, as there shown, the horizontal spacing action of the upper strips 33 being sufficient. Any desired number of transverse reenforcing and binding members such as rods 38, 38, may be inserted through certain of the cut-out spaces 40 to tie the parts together and further distribute theload laterally.

When lighter loads are to be carried the tension reenforcement .may consist merely of rods 32", as shown in Fig. 4:, supported from the upper grating by hooks 39 through the eyes 39 of which the rods 32 extend, while the hooked ends 39 pass through holes 36 in the straight bars 31 of the grating which forms the surface armor.

in laying or building up the slabs to form the bridge deck 43 it 1s important that the longitudinals of the surface grating extend lengthwise of the bridge, i. e. parallel to the fiow of traiflc, so that the wide tires of the wheels of heavy motor trucks may rest on as many of the grating bars as possible and so distribute the concentrated load on said wheels as widely as possible, thereby reducing the punching shear stressesv developed 20 ter.

shown in Fig. 2, produces a truss-like structure of great strength er unit of weight. These results are usu 1y attained the highest degree inthe form shown in Fig. 3. The rigidity so secured enables the bridge designer to specify deck slabs of much reduced thicknes and consequent less weight of concrete, and also to cut down the weight of reenforcing metal used in the structure shown in the above mentioned Irving patent to support a given load. This permits a correspondin reduction in the met-a1 needed for the bri ge girders, trusses or cables, towers, etc. which, in. turn, produces a further saving in dead load carried by the structure with the net result that the cost of the bridge parts, other than the decking or flooring, is reduced by an amount more than enough to pay for the cost of the lat Having described my invention, I claim: LA-structure adapted to serve as a reenforcementin concrete slabs, which structure comprises the combination of two similar gratings, each composed of a series of straight bars and a series of bent strips, each of which strips is located between, and fastened to, the straight bars of either side of it, a few of said straight bars uniformly spaced apart being wide enough to extend from one grating to the other and form an element in each, and having the portions between said gratings cut away into skeleton form. 1 v

2. The combination of a structure such as defined in. claim 1 with a bodyof concrete filling the meshes of said gratings, the space between said gratings and the cut away portions of said skeleton bars.

' JOHN A. VOSMP. 

